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Controlling RGB LEDs with only powerlines: Anatomy of a Christmas light string
- halpert 5y agoThe video of the manufacturing process is quite interesting. A lot of human labor is involved.
- HALtheWise 5y agoI'm really excited for the inevitable improved version of this that supports binary addresses and setting approximate PWM brightness levels. Given the manufacturing process[0] linked, it could be a _little_ tricky to actually assign a known ID to each light in the strand, but either using the placement order when the strand is made or using a stochastic process to randomize the IDs and subsequently calibrate the strand should be viable, and result in a low cost strand with WS2812-like capabilities. [0]: https://youtu.be/wCKlCUBsaT4 https://youtu.be/wCKlCUBsaT4
- londons_explore 5y agoThis string is only "slightly addressable" - in a string of 100 LEDs, you can't display any arbitrary image. With small changes though, they could have allowed arbitrary addressing, which would have made these LEDs applicable for a far wider variety of products. One way would be to deliberately make the string of LED's reflect the signal back from the unterminated end of the string. Then, make each LED only respond if the reflection and original signal add up past a threshold. The controller can then have an initialisation step where it 'discovers' all the functioning LED's and their position on the line (by looking at the power draw when commanding them to turn on). The downside is you'd be sending GHz bandwidth pulses down a poorly controlled pair of wires, and sharp bends and stuff might leak rather a lot of RF.
- HPsquared 5y agoThis is modern electronic design in a nutshell. The large-scale physical design is as simple as possible (just regular wiring), the individual components are all "smart" (Christmas lights each with their own integrated IC, doesn't get more embedded than that) and addressable via a communication protocol. Imagine how difficult the wiring would be to have 100 addressable lights that didn't use this arrangement!
- kurthr 5y agoWhat is interesting is that one could in fact do this with a single wire. You might eventually see something like this for micro-LED display solutions. The key is to drive a current and control the voltage at both ends of a string such that each LED detects modulation and bypasses (itself) or consumes power (in-line). That might be relevant where the strength of a single (e.g. steel) wire was used to support a long string. By driving relatively low (max RGB) current at higher voltages and time (e.g. PWM) sequencing the light modulation. In a simple case, imaging there are 100 RGB lights, half of them excited on each polarity and bypassed with a 0.2V Schottky stacking to +/-10V minimum (for digital data) at <100mA. You might synchronize and send data to the smart lights each "zero crossing" and get away +/-50Vpp for the string by only having 10 (12.5%) stacked (inline) on at any one time (a controller for the LED FETs can stay awake on a capacitor). As long as you run at a few kHz you won't have noticeable flicker, capacitive and you can update with a few bits per light each cycle. More complex designs could use FETs to improve data link efficiency of the minimum voltage and higher current (lower PWM times) could substantially reduce peak voltage to +/-5V or so.
- IgorPartola 5y agoYou don’t need individual data lines to address each LED. A serial bus and a microcontroller would be enough. The only difference is that here there is no dedicated data line/lines. 1-wire is a similarly clever protocol.
- wyager 5y agoIn 10 years every one of these LEDs will be running an IPv6 stack, and they'll still be using the same wire-and-glue construction.
- mrintellectual 5y agoI love electronics and electrical engineering in general. But this article explains perfectly why it is less accessible than software engineering - the former requires a individual components, soldering iron(s), a digital oscilloscope, etc. while all you need is access to a computer with internet for the latter.
- kken 5y agoI think it has never been easier to enter electronics (especially embedded stuff) than it is now. You can get a starter set including RPI/Arduino/Breakboard/Components for less than $100. Also, with a breadboard no soldering iron is needed. Try chemistry, mining, process engineering or even mechanical engineering in comparison?
- spookthesunset 5y agoTotally agree. Electronics has never been easier thanks to low-cost microcontrollers like the ESP32. Most of the "electronics" you'll be doing is simply plumbing--connecting the GPIO outputs of your microcontroller to whatever peripherals you want to support. It's a good gateway into the wider world of electronics.
- jcun4128 5y agoI am curious what the next thing up is that is more "legit". At this time I've used Arduino/ESP/Teensy. I bought an STM32 and Beaglebone but wondering what does something like a Boston Dynamics dog use? Probably a full on processor like i7. Edit: oh it uses i5 with Ubuntu ha, plus separate graphics for the AI part
- buescher 5y agoChemistry takes some initiative these days, but the dark age after the golden age of chemistry sets is pretty much over. Mining, I dunno, buy a shovel? Hobby prospecting - sluicing and panning for gold, mostly - was still a thing in the rural west when I was a kid. I'd bet you could find a forum or something if you searched. Process engineering, I don't know what you'd want to do as a hobbyist. Mechanical engineering - 3d printers and chinese machine tools are affordable. It's never been easier to buy small parts and fasteners. The free finite element simulation packages are getting pretty good.
- Freak_NL 5y agoOne downside to this type of Christmas lights is that these design parameters — i.e., make it possible to manufacture feature-rich novelties with a minimum of wiring and changes to the assembly line — result in a product that has no user-serviceable parts: when a few LEDs die, the whole product should be thrown out. I say 'should' not because I think so, but because this is literally what is written on the labels affixed to many such products. We went from lights featuring incandescent light bulbs which came with a few spares in the box (anyone could replace those), to LED lights with a few spares (finicky to replace, but doable), to almost exclusively fixed-in-place LED lights without replacements and labels attached that tell the user to throw the chain out when lights break. And now more and more complexity with integrated ICs. Only those of us with a soldering iron can salvage some of them, and this new category seems like it might not be repairable at all (excepting the really clever EE folk like the author). Environmentally speaking, the increased complexity and focus on ease of manufacturing of such products seems to reduce their lifespan as well, with repairability already at a minimum.
- spookthesunset 5y agoDon't forget those old incandescent strings could draw up to 100 watts each! > And now more and more complexity with integrated ICs. I dunno. Which is more likely to fail? The older electromechanical "blinkers" they used or a solid state IC? I do get it though. Society is addicted to disposable things. But I'm not sure the problem is these things being non-user-servicable. When these things go, they go... Usually the cabling gets fucked on them long before the LED's.
- deleted 5y ago[deleted]
- IIAOPSW 5y agoThis is all true, but people voted for it with their wallets. At all levels, people understood that when their electronics break they would be paying for it again, making the ownership of the product more like renting with recurring payments. People understood the term "planned obsolescence". But they saw the cheap shinny blinky lights and decided they wanted it. The consumer is far more guilty than the company that gave them what they wanted.
- jhanschoo 5y agoThere's one part about the article that I'd like confirmation about: does this mean that the LEDs come out of the factory already configured as belonging to one of the 6 zones? This would be as opposed to, say, WS2812 LED packages where they are identical.